漫话Redis源码之二十四

redisProtocolToLuaType是一个转换寒山湖，跟lua相关：

/* Debugger shared state is stored inside this global structure. */
#define LDB_BREAKPOINTS_MAX 64  /* Max number of breakpoints. */
#define LDB_MAX_LEN_DEFAULT 256 /* Default len limit for replies / var dumps. */
struct ldbState {
    connection *conn; /* Connection of the debugging client. */
    int active; /* Are we debugging EVAL right now? */
    int forked; /* Is this a fork()ed debugging session? */
    list *logs; /* List of messages to send to the client. */
    list *traces; /* Messages about Redis commands executed since last stop.*/
    list *children; /* All forked debugging sessions pids. */
    int bp[LDB_BREAKPOINTS_MAX]; /* An array of breakpoints line numbers. */
    int bpcount; /* Number of valid entries inside bp. */
    int step;   /* Stop at next line regardless of breakpoints. */
    int luabp;  /* Stop at next line because redis.breakpoint() was called. */
    sds *src;   /* Lua script source code split by line. */
    int lines;  /* Number of lines in 'src'. */
    int currentline;    /* Current line number. */
    sds cbuf;   /* Debugger client command buffer. */
    size_t maxlen;  /* Max var dump / reply length. */
    int maxlen_hint_sent; /* Did we already hint about "set maxlen"? */
} ldb;
 
/* ---------------------------------------------------------------------------
 * Utility functions.
 * ------------------------------------------------------------------------- */
 
/* Perform the SHA1 of the input string. We use this both for hashing script
 * bodies in order to obtain the Lua function name, and in the implementation
 * of redis.sha1().
 *
 * 'digest' should point to a 41 bytes buffer: 40 for SHA1 converted into an
 * hexadecimal number, plus 1 byte for null term. */
void sha1hex(char *digest, char *script, size_t len) {
    SHA1_CTX ctx;
    unsigned char hash[20];
    char *cset = "0123456789abcdef";
    int j;
 
    SHA1Init(&ctx);
    SHA1Update(&ctx,(unsigned char*)script,len);
    SHA1Final(hash,&ctx);
 
    for (j = 0; j < 20; j++) {
        digest[j*2] = cset[((hash[j]&0xF0)>>4)];
        digest[j*2+1] = cset[(hash[j]&0xF)];
    }
    digest[40] = '\0';
}
 
/* ---------------------------------------------------------------------------
 * Redis reply to Lua type conversion functions.
 * ------------------------------------------------------------------------- */
 
/* Take a Redis reply in the Redis protocol format and convert it into a
 * Lua type. Thanks to this function, and the introduction of not connected
 * clients, it is trivial to implement the redis() lua function.
 *
 * Basically we take the arguments, execute the Redis command in the context
 * of a non connected client, then take the generated reply and convert it
 * into a suitable Lua type. With this trick the scripting feature does not
 * need the introduction of a full Redis internals API. The script
 * is like a normal client that bypasses all the slow I/O paths.
 *
 * Note: in this function we do not do any sanity check as the reply is
 * generated by Redis directly. This allows us to go faster.
 *
 * Errors are returned as a table with a single 'err' field set to the
 * error string.
 */
 
char *redisProtocolToLuaType(lua_State *lua, char* reply) {
 
    if (!lua_checkstack(lua, 5)) {
        /*
         * Increase the Lua stack if needed, to make sure there is enough room
         * to push 5 elements to the stack. On failure, exit with panic.
         * Notice that we need, in the worst case, 5 elements because redisProtocolToLuaType_Aggregate
         * might push 5 elements to the Lua stack.*/
        serverPanic("lua stack limit reach when parsing redis.call reply");
    }
 
    char *p = reply;
 
    switch(*p) {
    case ':': p = redisProtocolToLuaType_Int(lua,reply); break;
    case '$': p = redisProtocolToLuaType_Bulk(lua,reply); break;
    case '+': p = redisProtocolToLuaType_Status(lua,reply); break;
    case '-': p = redisProtocolToLuaType_Error(lua,reply); break;
    case '*': p = redisProtocolToLuaType_Aggregate(lua,reply,*p); break;
    case '%': p = redisProtocolToLuaType_Aggregate(lua,reply,*p); break;
    case '~': p = redisProtocolToLuaType_Aggregate(lua,reply,*p); break;
    case '_': p = redisProtocolToLuaType_Null(lua,reply); break;
    case '#': p = redisProtocolToLuaType_Bool(lua,reply,p[1]); break;
    case ',': p = redisProtocolToLuaType_Double(lua,reply); break;
    }
    return p;
}
 
char *redisProtocolToLuaType_Int(lua_State *lua, char *reply) {
    char *p = strchr(reply+1,'\r');
    long long value;
 
    string2ll(reply+1,p-reply-1,&value);
    lua_pushnumber(lua,(lua_Number)value);
    return p+2;
}
 
char *redisProtocolToLuaType_Bulk(lua_State *lua, char *reply) {
    char *p = strchr(reply+1,'\r');
    long long bulklen;
 
    string2ll(reply+1,p-reply-1,&bulklen);
    if (bulklen == -1) {
        lua_pushboolean(lua,0);
        return p+2;
    } else {
        lua_pushlstring(lua,p+2,bulklen);
        return p+2+bulklen+2;
    }
}
 
char *redisProtocolToLuaType_Status(lua_State *lua, char *reply) {
    char *p = strchr(reply+1,'\r');
 
    lua_newtable(lua);
    lua_pushstring(lua,"ok");
    lua_pushlstring(lua,reply+1,p-reply-1);
    lua_settable(lua,-3);
    return p+2;
}
 
char *redisProtocolToLuaType_Error(lua_State *lua, char *reply) {
    char *p = strchr(reply+1,'\r');
 
    lua_newtable(lua);
    lua_pushstring(lua,"err");
    lua_pushlstring(lua,reply+1,p-reply-1);
    lua_settable(lua,-3);
    return p+2;
}
 
char *redisProtocolToLuaType_Aggregate(lua_State *lua, char *reply, int atype) {
    char *p = strchr(reply+1,'\r');
    long long mbulklen;
    int j = 0;
 
    string2ll(reply+1,p-reply-1,&mbulklen);
    if (server.lua_client->resp == 2 || atype == '*') {
        p += 2;
        if (mbulklen == -1) {
            lua_pushboolean(lua,0);
            return p;
        }
        lua_newtable(lua);
        for (j = 0; j < mbulklen; j++) {
            lua_pushnumber(lua,j+1);
            p = redisProtocolToLuaType(lua,p);
            lua_settable(lua,-3);
        }
    } else if (server.lua_client->resp == 3) {
        /* Here we handle only Set and Map replies in RESP3 mode, since arrays
         * follow the above RESP2 code path. Note that those are represented
         * as a table with the "map" or "set" field populated with the actual
         * table representing the set or the map type. */
        p += 2;
        lua_newtable(lua);
        lua_pushstring(lua,atype == '%' ? "map" : "set");
        lua_newtable(lua);
        for (j = 0; j < mbulklen; j++) {
            p = redisProtocolToLuaType(lua,p);
            if (atype == '%') {
                p = redisProtocolToLuaType(lua,p);
            } else {
                if (!lua_checkstack(lua, 1)) {
                    /* Notice that here we need to check the stack again because the recursive
                     * call to redisProtocolToLuaType might have use the room allocated in the stack */
                    serverPanic("lua stack limit reach when parsing redis.call reply");
                }
                lua_pushboolean(lua,1);
            }
            lua_settable(lua,-3);
        }
        lua_settable(lua,-3);
    }
    return p;
}